`nx_audio_wav.nx` source

1// nx_audio_wav.nx -- SOVEREIGN AUDIO ENGINE rung R4: render to a real .wav file.
2//
3// Makes the engine produce a PLAYABLE artifact (the live-testable principle for
4// audio: the file is the proof).  WAV/RIFF is a STANDARD format -> sovereign
5// implementation, proven byte-exact vs the spec in the gate (per the non-novel
6// verification doctrine).  16-bit PCM, little-endian, interleaved stereo.  Only
7// % and / used (no reliance on bitwise).  license_tier: ORIGINAL.
8
9import "nx_syscalls.nx"
10const K_MAGIC_65536: i64 = 65536
11const K_MAGIC_16777216: i64 = 16777216
12
13// little-endian writers (header values are non-negative)
14func wav_put_u32(buf: *u8, off: i64, v: i64) -> i64 {
15    buf[off] = (v % 256) as u8
16    buf[off + 1] = ((v / 256) % 256) as u8
17    buf[off + 2] = ((v / K_MAGIC_65536) % 256) as u8
18    buf[off + 3] = ((v / K_MAGIC_16777216) % 256) as u8
19    return 0
20}
21func wav_put_u16(buf: *u8, off: i64, v: i64) -> i64 {
22    buf[off] = (v % 256) as u8
23    buf[off + 1] = ((v / 256) % 256) as u8
24    return 0
25}
26// signed 16-bit sample (handles negatives by wrapping into 0..65535 first)
27func wav_put_i16(buf: *u8, off: i64, v: i64) -> i64 {
28    let u: i64 = ((v % K_MAGIC_65536) + K_MAGIC_65536) % K_MAGIC_65536
29    buf[off] = (u % 256) as u8
30    buf[off + 1] = ((u / 256) % 256) as u8
31    return 0
32}
33func wav_put_str(buf: *u8, off: i64, s: *u8) -> i64 {
34    var i: i64 = 0
35    while s[i] != (0 as u8) { buf[off + i] = s[i]; i = i + 1 }
36    return i
37}
38
39// render n frames of 16-bit interleaved stereo WAV into out; returns total bytes
40func wav_render_stereo(L: *i64, R: *i64, n: i64, rate: i64, out: *u8) -> i64 {
41    let channels: i64 = 2
42    let bits: i64 = 16
43    let block_align: i64 = channels * (bits / 8)        // 4
44    let byte_rate: i64 = rate * block_align
45    let data_size: i64 = n * block_align
46    wav_put_str(out, 0, "RIFF" as *u8)
47    wav_put_u32(out, 4, 36 + data_size)
48    wav_put_str(out, 8, "WAVE" as *u8)
49    wav_put_str(out, 12, "fmt " as *u8)
50    wav_put_u32(out, 16, 16)                             // fmt chunk size
51    wav_put_u16(out, 20, 1)                              // PCM
52    wav_put_u16(out, 22, channels)
53    wav_put_u32(out, 24, rate)
54    wav_put_u32(out, 28, byte_rate)
55    wav_put_u16(out, 32, block_align)
56    wav_put_u16(out, 34, bits)
57    wav_put_str(out, 36, "data" as *u8)
58    wav_put_u32(out, 40, data_size)
59    var off: i64 = 44
60    var i: i64 = 0
61    while i < n {
62        wav_put_i16(out, off, L[i]); off = off + 2
63        wav_put_i16(out, off, R[i]); off = off + 2
64        i = i + 1
65    }
66    return off
67}
68
69func wav_save(path: *u8, buf: *u8, len: i64) -> i64 {
70    let fd: i64 = sys_openat_wr(path, 420)
71    if fd < 0 { return 0 - 1 }
72    var wr: i64 = 0
73    while wr < len { let c: i64 = sys_write(fd, buf + wr, len - wr); if c <= 0 { break } wr = wr + c }
74    sys_close(fd)
75    return wr
76}
nx_audio_wav.nx source

`nx_audio_wav.nx` source
